Issue with program.cs file in windows app

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Hello,

I developed an windows application.I used an background worker process in my code.
When i was working on my application suddenly it throws an error in program.cs file
Null reference exception was unhandled
Object reference not set to an instance of an object.

in application.run(); line how to fix this error.

[Edit- OPs code from his comment]

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;


namespace AISQBTool
{
    static class Program
    {
        ///
        /// The main entry point for the application.
        ///
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Login());
        }
    }
}

Posted 18-Feb-13 21:02pm

karteekboddu

Updated 19-Feb-13 3:13am

CHill60

v2

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Comments

Richard MacCutchan 19-Feb-13 3:40am

Find the reference that has not been initialised and correct the code. Without seeing the actual lines of code we cannot begin to guess what may be happening.

Jibesh 19-Feb-13 3:45am

It's not the Application.Run. it might be somewhere in your Form class. Error like these are easy to identify and resolve. debug your application and check which part of the code these exceptions are throwing.

OriginalGriff 19-Feb-13 3:47am

Without seeing the code which generated the error, we cannot help you.
Use the "Improve question" widget to edit your question and provide better information.

S. M. Ahasan Habib 19-Feb-13 4:35am

Just post your code. You may debug the code and find out the line/object where object reference null found. If you identify object which is throwing null reference exception, hope you can solve it by your own.

[no name] 19-Feb-13 6:20am

can you provide your program.cs code ovrr here..??

karteekboddu 19-Feb-13 7:11am

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace AISQBTool
{
static class Program
{
///

/// The main entry point for the application.
///

[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Login());
}
}
}

[no name] 19-Feb-13 7:15am

make sure you have a form named with login.

karteekboddu 19-Feb-13 7:26am

yes i had

CHill60 19-Feb-13 9:16am

In your debugger put a breakpoint on Application.Run(new Login()); and run your code. When you get to that line hit F11 to step into the function and keep hitting F11 until you get the error. Then post that line of code

karteekboddu 20-Feb-13 1:39am

at System.Windows.Forms.DataGridViewRowHeaderCell.PaintPrivate(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, Int32 rowIndex, DataGridViewElementStates dataGridViewElementState, Object formattedValue, String errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts, Boolean computeContentBounds, Boolean computeErrorIconBounds, Boolean paint)
at System.Windows.Forms.DataGridViewRowHeaderCell.Paint(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, Int32 rowIndex, DataGridViewElementStates cellState, Object value, Object formattedValue, String errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
at System.Windows.Forms.DataGridViewCell.PaintWork(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, Int32 rowIndex, DataGridViewElementStates cellState, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
at System.Windows.Forms.DataGridViewRow.PaintHeader(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow, DataGridViewPaintParts paintParts)
at System.Windows.Forms.DataGridViewRow.Paint(Graphics graphics, Rectangle clipBounds, Rectangle rowBounds, Int32 rowIndex, DataGridViewElementStates rowState, Boolean isFirstDisplayedRow, Boolean isLastVisibleRow)
at System.Windows.Forms.DataGridView.PaintRows(Graphics g, Rectangle boundingRect, Rectangle clipRect, Boolean singleHorizontalBorderAdded)
at System.Windows.Forms.DataGridView.PaintGrid(Graphics g, Rectangle gridBounds, Rectangle clipRect, Boolean singleVerticalBorderAdded, Boolean singleHorizontalBorderAdded)
at System.Windows.Forms.DataGridView.OnPaint(PaintEventArgs e)
at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
at System.Windows.Forms.Control.WmPaint(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.DataGridView.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at AISQBTool.Program.Main() in C:\Users\AISC01\Desktop\AISQBTool_11-2-13_integrated\AISQBTool_11-2-13_integrated\AISQBTool\Program.cs:line 22

CHill60 20-Feb-13 4:16am

Ok - it was the line of code I was after not the exception - plus the first line of the exeception is usually the most useful bit but is missing here. From what I see here - do you actually have a DataGridView on your Login form?

karteekboddu 20-Feb-13 5:40am

No i didnt had gridview in login form

CHill60 20-Feb-13 5:45am

Try replacing the ex.StackTrace from the solution below with ex.Message and post that result here. Also - please follow my advice on debugging and post the line of code that causes the problem as well. We can't help if we can't see the code!

karteekboddu 20-Feb-13 6:11am

I used ex.message
ex.Message = "Object reference not set to an instance of an object."

CHill60 20-Feb-13 6:17am

And the line of code ?

karteekboddu 20-Feb-13 6:21am

Application.Run(new Login());

CHill60 20-Feb-13 6:29am

In your debugger put a breakpoint on Application.Run(new Login()); and run your code. When you get to that line hit F11 to step into the function and keep hitting F11 until you get the error. Then post THAT line of code

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Jegan Thiyagesan · Answer 1 · 2013-02-19T03:16:00

Solution 1

Hi Catch the exception and see where is the issue actually occured.

C#

[STAThread] 
static void Main() 
{ 
    try
    {
        Application.EnableVisualStyles(); 
        Application.SetCompatibleTextRenderingDefault(false); 
        Application.Run(new Login()); 
    }
    Catch (Exception ex)
    {
        Console.Out.WriteLine(ex.StackTrace);
    }
}

The stcktrace will tell you at which line in which file the code failed.

Regards
Jegan

Posted 19-Feb-13 3:16am

Jegan Thiyagesan

Comments

Jegan Thiyagesan 20-Feb-13 9:08am

Hithe stack trace is telling you that some unsafe native method is being called.

System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(Form mainForm) at AISQBTool.Program.Main() in C:\Users\AISC01\Desktop\AISQBTool_11-2-13_integrated\AISQBTool_11-2-13_integrated\AISQBTool\Program.cs:line 22

Can you post some code from your "Login" class?

karteekboddu 20-Feb-13 9:28am

This was the code from Login class

private void btnLogin_Click(object sender, EventArgs e)
{
try
{

string user = txtUser.Text.ToString();

//Constructing connection string from the inputs
if (user == "SYS" || user == "sys" || user == "sys as sysdba")
{
StringBuilder Con = new StringBuilder("Data Source=");
Con.Append(txtTns.Text);
Con.Append(";User ID=");
Con.Append(txtUser.Text);
Con.Append(";Password=");
Con.Append(txtPassword.Text);
Con.Append(";DBA Privilege=SYSDBA");
string strCon = Con.ToString();
var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
connectionStringsSection.ConnectionStrings["con"].ConnectionString = strCon;
connectionStringsSection.ConnectionStrings["newcon"].ConnectionString = strCon;
config.Save();
ConfigurationManager.RefreshSection("connectionStrings");
// updateConfigFile(strCon);

ConfigurationManager.RefreshSection("connectionStrings");

}
else
{
StringBuilder Con1 = new StringBuilder("Data Source=");
Con1.Append(txtTns.Text);
Con1.Append(";User ID=");
Con1.Append(txtUser.Text);
Con1.Append(";Password=");
Con1.Append(txtPassword.Text);

string strCon1 = Con1.ToString();
var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
connectionStringsSection.ConnectionStrings["con"].ConnectionString = strCon1;
connectionStringsSection.ConnectionStrings["newcon"].ConnectionString = strCon1;
config.Save();
ConfigurationManager.RefreshSection("connectionStrings");

}
//QBHomep home = new QBHomep();
QueryBuilder home = new QueryBuilder();
this.Cursor = System.Windows.Forms.Cursors.WaitCursor;
home.Show();
this.Hide();
}
catch (Exception E)
{
MessageBox.Show(ConfigurationManager.ConnectionStrings["con"].ToString() + ".This is invalid connection", "Incorrect server/Database");
}
}

public void updateConfigFile(string con)
{
//updating config file
XmlDocument XmlDoc = new XmlDocument();
//Loading the Config file
string path = "..\\..\\App.config";
XmlDoc.Load(path);
foreach (XmlElement xElement in XmlDoc.DocumentElement)
{
if (xElement.Name == "connectionStrings")
{
//setting the coonection string
xElement.FirstChild.Attributes[1].Value = con;
xElement.LastChild.Attributes[1].Value = con;

}
}
//writing the connection string in config file
XmlDoc.Save(path);

}

private void btnCancel_Click(object sender, EventArgs e)
{
this.Close();
}

//protected override void OnPaintBackground(PaintEventArgs e)
//{
// using (LinearGradientBrush brush = ne

Jegan Thiyagesan 20-Feb-13 9:35am

Where is the Login() constructor?, the code above looks like missing half the page.

karteekboddu 20-Feb-13 9:40am

Sorry,
public Login()
{

InitializeComponent();
this.txtPassword.KeyPress += new KeyPressEventHandler(CheckKeys);
}

private void CheckKeys(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
if (e.KeyChar == (char)13)
{

try
{
string user = txtUser.Text.ToString();

//Constructing connection string from the inputs
if (user == "SYS" || user == "sys" || user == "sys as sysdba")
{
StringBuilder Con = new StringBuilder("Data Source=");
Con.Append(txtTns.Text);
Con.Append(";User ID=");
Con.Append(txtUser.Text);
Con.Append(";Password=");
Con.Append(txtPassword.Text);
Con.Append(";DBA Privilege=SYSDBA");
string strCon = Con.ToString();
var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
connectionStringsSection.ConnectionStrings["con"].ConnectionString = strCon;
connectionStringsSection.ConnectionStrings["newcon"].ConnectionString = strCon;
config.Save();
ConfigurationManager.RefreshSection("connectionStrings");
// updateConfigFile(strCon);

ConfigurationManager.RefreshSection("connectionStrings");

}
else
{
StringBuilder Con1 = new StringBuilder("Data Source=");
Con1.Append(txtTns.Text);
Con1.Append(";User ID=");
Con1.Append(txtUser.Text);
Con1.Append(";Password=");
Con1.Append(txtPassword.Text);

string strCon1 = Con1.ToString();
var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
connectionStringsSection.ConnectionStrings["con"].ConnectionString = strCon1;
connectionStringsSection.ConnectionStrings["newcon"].ConnectionString = strCon1;
config.Save();
ConfigurationManager.RefreshSection("connectionStrings");

}
//QBHomep home = new QBHomep();
QueryBuilder home = new QueryBuilder();
this.Cursor = System.Windows.Forms.Cursors.WaitCursor;
home.Show();
this.Hide();
}
catch (Exception E)
{
MessageBox.Show(ConfigurationManager.ConnectionStrings["con"].ToString() + ".This is invalid connection", "Incorrect server/Database");
}
}

Jegan Thiyagesan 20-Feb-13 9:52am

Can you put a break point in "InitialiseComponent()" and run the app, If it does stops at that break point, press the F11 key to step into that method and continue F11 until the exception throws, note down the line that the exception throwed. If the Break point doesn't get hit, then let us know.

karteekboddu 20-Feb-13 10:07am

I ran app by keeping break point but it is not throwing any error.
But in runtime its giving exception like OBJECT REFERENCE NOT SET TO INSTANCE OF OBJECT or
some times ARGUMENT EXCEPTION UNHANDLED like INDEX WAS OUT OF RANGE

Jegan Thiyagesan 20-Feb-13 10:24am

Where did you add break points?
Are you using any third party dlls?

karteekboddu 21-Feb-13 1:50am

Yes like fast colored textbox dll

Jegan Thiyagesan 21-Feb-13 5:18am

Have you tried using the .NEt textbox to eliminate the scenario that the dll might be causing the problem?

CHill60 · Answer 2 · 2013-02-20T00:41:00

We're getting no where fast here without seeing any code. Try the following...

1. Create a new application
2. Add a Login form - do not use the Login form from the program you're having the problem with
3. Add all of the controls you need onto that form but do not add any other code
4. Run the new program and confirm that it does not throw the exception
5. Add any other code you have in the original Login form one bit at a time
6. After adding each code segment run the program to confirm it does not throw the exception
- If it does throw an exception then you know exactly which piece of code is causing the problem.
7. If it doesn't throw an exception then you need to compare the Form1.Designer.cs files from both projects (and possibly Form1.cs also) - when you find the differences then you will know where the problem lies and should be able to solve the problem

MalwareTrojan · Answer 3 · 2013-02-20T00:49:00

Solution 3

Check Class file of your database, Check variable Spellings and Datatype of Varaible with its respective property.

Or another way is,
you must be passing null values into the database which is NOT NULL.

Posted 20-Feb-13 0:49am

MalwareTrojan

Comments

CHill60 20-Feb-13 8:38am

I don't think he would be getting an exception mentioning DataGridView if it was a database issue?

Issue with program.cs file in windows app

3 solutions

Solution 1

Solution 2

Solution 3

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